A World Health Organization team emerged from their 14-day quarantine in the Chinese city of Wuhan on Thursday to begin field work in their investigation of the origins of the virus that cause the COVID-19 pandemic.

China's COVID-19 regulations required all members of the team to complete 14 days of quarantine upon their arrival. They have been taking part in virtual meetings during the quarantine period.

The researchers were seen leaving their hotel and boarding a bus on Thursday afternoon.

ABC News' Karson Yiu contributed to this report.

There were 152,478 new cases of COVID-19 confirmed in the United States on Wednesday, according to a real-time count kept by Johns Hopkins University.

Wednesday's case count is far less than the country's all-time high of 300,282 newly confirmed infections on Jan. 2, Johns Hopkins data shows.

An additional 3,943 fatalities from COVID-19 were registered nationwide on Wednesday, down from a peak of 4,466 new deaths on Jan. 12, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the Martin Luther King Jr. Day holiday weekend.

A total of 25,598,062 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 429,195 have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4, then reaching 200,000 on Nov. 27 before topping 300,000 on Jan. 2.

So far, the U.S. Food and Drug Administration has authorized two COVID-19 vaccines for emergency use -- one developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech, and another developed by American biotechnology company Moderna and the National Institute of Allergy and Infectious Diseases. More than 24 million vaccine doses have been administered nationwide, according to the latest data from the Centers for Disease Control and Prevention.

A draft request for assistance between the Federal Emergency Management Agency and the U.S. Department of Defense is under discussion that would seek as many as 10,000 service members to support administering COVID-19 vaccine shots up at 100 sites nationwide, according to a FEMA official who spoke on condition of anonymity because the details were not final.

A defense official, who also spoke on condition of anonymity, confirmed discussions are under way, but the final number of personnel is not settled.

It is also unclear what kind of active duty or National Guard mix it could be, and whether it includes National Guardsmen already helping in the vaccine effort around the country.

ABC News' Matthew Vann and Luis Martinez contributed to this report.

Dr. Anthony Fauci, chief medical adviser to U.S. President Joe Biden, told Fox News' "America Reports With John Roberts & Sandra Smith" that there’s no official recommendation yet on wearing double masks.

"The CDC doesn't officially recommend wearing double masks," Fauci said. "You know what would be a good start? If everybody wears at least one mask."

ABC News’ Anne Flaherty contributed to this report.

Russia said Friday it will be ready to supply Europe with enough doses of its COVID-19 vaccine, Sputnik V, for 50 million people in the second quarter of this year.

The Russian Direct Investment Fund (RDIF), which is responsible for worldwide marketing of the vaccine, announced via Twitter that 100 million doses can be provided to the European Union -- pending regulatory approval -- once most of Russia's population has been vaccinated.

After being developed by the state-run Gamaleya Research Institute of Epidemiology and Microbiology in Moscow, Sputnik V was controversially registered by the health ministry in August before starting crucial Phase 3 trials, with Russia declaring itself the first in the world to register a COVID-19 vaccine.

The RDIF said the vaccine is now registered in 15 countries and that documents have been submitted to the European Medicines Agency (EMA) for "rolling review," which would mean that the drug regulator is reviewing clinical trial data on a rolling basis. However, last week, the EMA said in a statement that "currently Sputnik V is not undergoing a rolling review."

ABC News' Alina Lobzina contributed to this report.